Chuck actuator

Abstract

A chuck actuator has a main housing, a tube shaft having an outer end adjacent the main housing and an inner end remote from the main housing, a core shaft axially displaceable in the tube shaft between advanced and retracted positions, and a holding device on the outer shaft ends engageable with a tool or workpiece for holding same in the retracted position of the core shaft. A coupling member fixed on the core-shaft rear end and a housing member limitedly axially displaceable relative to the main housing and juxtaposed with the coupling member have formations including a radially projecting lug on one of the members and a radially open groove on the other of the members receiving the lug with play so that the lug can move limitedly axially in the groove. An actuating body axially displaceable in the main housing has a surface axially engageable with the coreshaft rear end and a pair of inwardly directed surfaces respectively engageable with the housing member and main housing. The surfaces are spaced such that, when one of the surfaces bears axially inward on the main housing, the other of the surfaces bears axially inward on the housing member to displace it axially inward and generally center the lug in the groove. The actuating body is moved outward to displace the core shaft into the advanced position and inward to allow the core shaft to move into the retracted position and displace the housing member to center the lug in the groove.

I claim:  
     
       1. A chuck actuator comprising: 
       a main housing;  
       a tube shaft having an outer end adjacent the main housing and an inner end remote from the main housing, and centered on an axis;  
       a core shaft axially displaceable in the tube shaft between advanced and retracted positions and also having an inner end at the main housing and an outer end;  
       a holding device on the outer ends engageable with a tool or workpiece for holding same in the retracted position of the core shaft;  
       a coupling member fixed on the core-shaft rear end;  
       a housing member limitedly axially displaceable relative to the main housing and juxtaposed with the coupling member;  
       formations including a radially projecting lug on one of the members and a radially open groove on the other of the members receiving the lug and of an axial dimension substantially greater than an axial dimension of the lug, whereby the lug can move limitedly axially in the groove;  
       an actuating body axially displaceable in the main housing, having a surface axially engageable with the core-shaft rear end, and having a pair of inwardly directed surfaces respectively engageable with the housing member and main housing, the surfaces being spaced such that when one of the surfaces bears axially inward on the main housing the other of the surfaces bears axially inward on the housing member to displace it axially inward and generally center the lug in the groove; and  
       means for moving the actuating body outward to displace the core shaft into the advanced position and inward to allow the core shaft to move into the retracted position and to displace the housing member to center the lug in the groove.  
     
     
       2. The chuck actuator defined in claim  1  wherein the main housing and housing member form a cylinder, the actuating body being a piston axially displaceable in the cylinder and having an outer face forming the other surface. 
     
     
       3. The chuck actuator defined in claim  2  wherein the main housing is provided with a pair of inlets connected to respective compartments formed by the piston in the cylinder. 
     
     
       4. The chuck actuator defined in claim  1  wherein the piston has a stem projecting axially outward through the main housing and forming the one surface. 
     
     
       5. The chuck actuator defined in claim  1  wherein the main housing is formed with a sleeve extending axially outward and forming a guide on which the housing member is slidable. 
     
     
       6. The chuck actuator defined in claim  1  wherein the main housing is formed with a radially inwardly open pocket and the housing member is provided with a radially outwardly projecting lug engaged in the pocket and limitedly axially displaceable therein, whereby axial travel of the housing member relative to the main housing is limited by the lug and pocket. 
     
     
       7. The chuck actuator defined in claim  1  further comprising: 
       a detectable element axially fixed on the outer shaft; and  
       means in including a sensor for detecting the element on the housing member.  
     
     
       8. A method of securing a workpiece or tool in a holding device of a chuck actuator including 
       a main housing;  
       a tube shaft having an outer end adjacent the main housing and an inner end remote from the main housing and centered on an axis;  
       a core shaft axially displaceable in the tube shaft between advanced and retracted positions and also having an inner end at the main housing and an outer end remote from the main housing, the holding device being mounted on the outer ends and engageable with a tool or workpiece for holding same in the retracted position of the core shaft;  
       a coupling member fixed on the core-shaft rear end;  
       a housing member limitedly axially displaceable relative to the main housing and juxtaposed with the coupling member, the main housing and housing member forming a cylinder;  
       formations including a radially projecting lug on one of the members and a radially open groove on the other of the members receiving the lug and of an axial dimension substantially greater than an axial dimension of the lug, whereby the lug can move limitedly axially in the groove; and  
       a piston axially displaceable in the main housing, having a surface axially engageable with the core-shaft rear end, subdividing the cylinder into inner and outer compartments, and having a pair of inwardly directed surfaces respectively engageable with the housing member and main housing, the surfaces being spaced such that when one of the surfaces bears axially inward on the main housing the other of the surfaces bears axially inward on the housing member to displace it axially inward and generally center the lug in the groove, the method comprising the step of  
       pressurizing the outer compartment to shift the piston inward, move the core shaft into the retracted position, engage the other surface with the housing member to center the lug in the groove, and finally engage the one surface with the main housing to arrest the piston with the lug centered in the groove.  
     
     
       9. A method of release a workpiece or tool from a holding device of a chuck actuator including 
       a main housing;  
       a tube shaft having an outer end adjacent the main housing and an inner end remote from the main housing and centered on an axis;  
       a core shaft axially displaceable in the tube shaft between advanced and retracted positions and also having an inner end at the main housing and an outer end remote from the main housing, the holding device being mounted on the outer ends and engageable with a tool or workpiece for holding same in the retracted position of the core shaft;  
       a coupling member fixed on the core-shaft rear end;  
       a housing member limitedly axially displaceable relative to the main housing and juxtaposed with the coupling member, the main housing and housing member forming a cylinder;  
       formations including a radially projecting lug on one of the members and a radially open groove on the other of the members receiving the lug and of an axial dimension substantially greater than an axial dimension of the lug, whereby the lug can move limitedly axially in the groove; and  
       a piston axially displaceable in the main housing, having a surface axially engageable with the core-shaft rear end, subdividing the cylinder into inner and outer compartments, and having a pair of inwardly directed surfaces respectively engageable with the housing member and main housing, the surfaces being spaced such that when one of the surfaces bears axially inward on the main housing the other of the surfaces bears axially inward on the housing member to displace it axially inward and generally center the lug in the groove, the method comprising the step of  
       pressurizing the inner compartment to shift the piston outward, move the surfaces out of engagement with the housing member and main housing, and engage the lug with an outer end of the groove.